The Mets have placed right-handed reliever Sean Green on the disabled list and purchased the contract of left-hander Raul Valdes from Triple-A Buffalo.

Green said Sunday that he has some tightness in his right side, although he’s unsure precisely what is causing the problem. He pitched one inning Wednesday against Florida, so his trip to the DL will be retroactive to April 8.

Valdes arrived in time for Sunday’s game against the Nationals. Green beat out the former Cuban defector for the last spot in the bullpen coming out of spring training.

Mets manager Jerry Manuel says the move means left-hander Pedro Feliciano will get most of the eighth-inning opportunities ahead of closer Francisco Rodriguez.